The science behind handshakes

A new study suggests shaking hands is more than just a common greeting.

Researchers at Israel's Weizmann Institute of Science say it's actually a way of smelling each other - much like animals do to learn more about one another. Except people are much more discreet.

The researchers used hidden cameras to observe more than 270 people while they waited alone. During that time the volunteers put their hands near their nose 22 percent of the time. Using some sneaky instrument that measured airflow to the nose, researchers realized they were actually sniffing their hands. Staff members eventually greeted some volunteers with a handshake. Participants who shake hands with someone of the same sex were twice as likely to subtly sniff their hands after.

Participants who shook hands with the opposite sex, however, were more likely to sniff their non-shaking hand.

The project's researcher told New Scientist, "People constantly have a hand at their face, they are sniffing it, and they modify that behavior after shaking hands. That demonstrates that the handshaking is a chemosignalling behavior."

Chemosignals are like pheromones that transmit information from our bodies - like sweating when we're afraid. New Scientist reports it's still unclear what chemical signals are exchanged through handshakes, or why there are different results for same-sex and cross-gender handshakes, but the team at Weizmann is now looking at how the signals might be affected in behavioral conditions like autism spectrum disorders.